ASP stimulates glucose transport in cultured human adipocytes.

The purpose of the present study was to examine the effect of Acylation Stimulating Protein (ASP) on glucose transport in cultured subcutaneous adipocytes. Subcutaneous adipose tissue was obtained from non-obese, healthy females (18-32 y old) undergoing mammoplasty reduction. Preadipocytes were isolated and differentiated into adipocytes. Following the exposure of preadipocytes and adipocytes to ASP or insulin, glucose transport was assessed as [3H] 2-deoxy glucose uptake. The measurements were normalised per total cell protein. ASP increases specific membrane glucose transport in both preadipocytes and adipocytes in a time and concentration dependent manner. Stimulation in both cell types is rapid (within minutes), reaching a maximal effect between 1 and 4 h. However, after 24 h exposure to ASP, there is a downregulation in the response. The ASP response is greater following differentiation of preadipocytes to adipocytes and is compared to that of insulin. Dose response studies demonstrated a five-fold greater sensitivity of adipocytes (half-maximal concentration of ASP on adipocytes = 0.5 microM, preadipocytes = 2.3 microM). These results demonstrate that ASP not only stimulates triglyceride synthesis, but also glucose transport in differentiated human adipocytes and is consistent with a physiologically important role for ASP in postprandial energy storage.